Letter, from Antoni van Leeuwenhoek to the Royal Society, dated at Delft Signed autograph Experiments with magnets; explanations of a meniscus in a glass; observations of patients who have been given 'sympathetic' powder (solution based on copper sulphate) as a medicine No original figures attached See EL/L3/2 for English translation Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 12, p 137 Translated extract in 'Philosophical Transactions', vol 19, no 227, p 512 5 April 1697